After a Russian missile struck a well-liked restaurant on Tuesday night in the Ukrainian city of Kramatorsk, 11 people died, including three teenagers.
Yuliya and Anna Aksenchenko, twins aged 14, were among the fatalities.
At least 57 other people were hurt, including residents of Colombia and a well-known Ukrainian author.
Volodymyr Zelensky, president of Ukraine, declared that Russia only deserved "defeat and a tribunal" for carrying out the attack.
The search and rescue operations are still ongoing, according to emergency services on Wednesday.
Kramatorsk, a city in the Donetsk region in the east, is occupied by the Ukrainian government but is close to Russian territory.
The education division of the Kramatorsk City Council issued a statement saying, "Russian missiles stopped the beating of the hearts of two angels.".
Despite being inside the restaurant on Tuesday night when it was attacked, former Colombian peace mediator Sergio Jaramillo Caro told the BBC that he only suffered minor wounds.
They are however seated next to a renowned Ukrainian author who is "fighting for her life" and whose identity is being withheld.
Mr. Jaramillo Caro requested prayers for her.
A local of Kramatorsk named Valentina, who runs a café close by, described the attack's aftermath damage. "Everything has been destroyed there; there are no windows or doors," she claimed.
The Russian defense ministry claimed it had destroyed a "temporary deployment of [Ukrainian] commanders" in Kramatorsk without going into further detail, and the Kremlin reiterated its claim that it only carried out strikes on military targets.
According to Yuri Sak, an adviser to the Ukrainian defense ministry, the country's air defenses are currently "insufficient to cover the full territory of Ukraine.".
In order to defend itself against Russian attacks, Ukraine keeps requesting that its allies give it modern fighter jets.
Last month, the US announced that it would assist the war-torn nation by allowing Western allies to supply F16s made in the United States and by providing Ukrainian pilot training for the aircraft.